1. Field of the Invention
The present invention relates generally to a method for lining a tubular member, such as a chemical pipeline, with a synthetic liner, the liner being fed along a variable angular path to the interior of the pipe to be lined and being secured within the pipe interior without the necessity of heat, vacuum or chemical bonding agents.
2. Description of the Prior Art
Fluid carrying pipes are often subject to deterioration, corrosion and other conditions which are detrimental to the life of the pipe or to the fluids moving through the pipe. This problem is particularly acute in many chemical process industries where caustic chemicals are being transported through pipelines. Modern chemical plants often include miles of pipeline subject to corrosion and deterioration. The pipelines needing lining may be buried below ground, elevated above ground, or be in storage racks.
Other chemical pipelines which are encompassed by the present invention include sewer pipes, water mains or gas mains, where foreign agents such as plant roots often break through the pipe wall and intrude into the pipe interior, thereby destroying the integrity of the pipe. Other factors such as differential pressures internally and externally of the pipe, erosion or earth movements can form leaks in the pipework which must be repaired. If excavating, uncoupling, replacing and backfilling of the pipework is required, the process is usually time consuming and expensive. An alternative solution is to provide an internal lining to the pipework to remedy leakage problems.
Although plastic inserts have been used in the past for protective purposes, their use has generally involved cumbersome and difficult procedures for effectively installing such liners, and particularly in sealing them to the wall of the pipe.
U.S. Pat. No. 3,494,813, to Lawrence et al., issued Feb. 10, 1970, shows a method for installing a plastic liner in a pipe by using vacuum to draw the liner into the pipe and to assure tight sealing engagement between the liner and the pipe wall.
U.S. Pat. No. 1,708,141, to Kepler, issued Apr. 9, 1929, shows a method of lining a pipe with an elastomeric lining in which the lining is pushed through a reducing die and coated with cement.
U.S. Pat. No. 3, 462,825, to Pope et al., issued Aug. 26, 1969, shows a method for lining a tubular member with a fluorocarbon liner having an initial outside diameter greater than the inside diameter of the tubular member. The liner is placed in the tubular member by gripping one end of the liner and pulling it through a reducing die and into the tubular member. The liner is then released, allowing it to expand into engagement with the inner wall of the tubular member.
British application, GB 2084686, filed Sep. 25, 1990, shows a method for lining sewer pipes in which a liner is pushed through downsizing rollers and fed into the pipe with heat being used to cause reverse expansion of the liner. Since the liner is fed approximately linearly into the underground pipe, it was necessary to excavate a sizeable opening in the surface of the ground for feeding the liner into the pipe interior.
None of the above methods succeed in providing an improved method for lining a tubular member with a synthetic liner in which the primary mechanism for securing the liner within the tubular member is the radial pressure exerted on the tubular member by the synthetic liner, the liner being in a state of circumferential compression within the surrounding tubular member when installed.
None of the above methods provides a convenient method for installing a liner in a tubular member wherein the liner is fed in a variable angular path toward the tubular member to be lined to thereby facilitate the lining of tubular members which are located below ground, or at various elevations above ground.
A need exists, therefore for a method for lining chemical or other pipelines in which the liner is installed without the use of chemical bonding agents and without the use of heat or vacuum pressure.
A need also exists for a method for lining an underground pipe which requires minimum excavation of the ground surface surrounding the point of liner insertion into the interior of the pipe.
A need also exists for a method for lining chemical or other pipelines which allows the liner to be guided through a variety of angular orientations toward the interior of the pipeline to be lined.